This invention relates generally to electrical switches of the snap action type such as are connected for actuation to a float bulb to operate a sump pump. More specifically, this invention relates to a single pole, single throw, sump pump switch which uses a float bulb actuator arm to directly actuate a single electrically conductive switch contact arm to turn the switch on and off without the need for a rigid contact arm carrier or support structure.
Sump pump switches of the double pole, double throw type, which use a float bulb operated, pivotal actuator arm in combination with a pivot bushing and compression spring to actuate a support member carrying a pair of spaced apart electroconductive contact arms have long been known and used in the prior art. See, for example, U.S. Pat. No. 4,196,325 granted to S. A. Povilaitis on Apr. 1, 1980, and U.S. Pat. No. 4,916,274 granted to R. H. Hawley et al. on Apr. 10, 1990. All of the prior art sump pump switches known to us are of the double pole, double throw type and none are believed to be of the single pole, single throw type. A problem encountered when using these prior art sump pump switches as intended, is that the ground lead for the electrical service line to the sump pump is broken or interrupted when the hot lead is opened. While this may have been the usual practice in the past, it is clearly not good practice as the ground wire should never be broken or interrupted, even if only on a momentary basis. But if the ground lead is not to be broken, then there is no need for a double pole, double throw sump pump switch, at least insofar as 120 volt a.c. sump pumps are concerned.
Another difficulty encountered with prior art sump pump switches is that the movable electrical contact arms thereof are not directly actuated to move between their on and off positions by an actuator arm. Rather, the contact arms are carried by a rigid support and it is this rigid support that is moved by an actuator arm acting through a pivot bushing and compression spring, which support then moves the contact arms which are attached thereto. Certainly, where a single pole, single throw sump pump switch is concerned, we have found that there is no need for a rigid contact arm support or carrier and the single electrically conductive contact arm can be directly actuated by the actuator arm, pivot bushing and compression spring combination without the need for the support or carrier component.
Yet another difficulty encountered with prior art sump pump switches is that the carrier or support structure is operatively connected to the actuator arm, bushing and spring combination near or approximately on a transverse line extending between the two moving contacts of the contact arms so that there is virtually no lever arm, or, at most, only a very small one, between the pivot point of the carrier and the movable contacts on the contact arms. As a result, the force of engagement and disengagement of the movable contacts with a corresponding set of fixed contacts is relatively small.
By means of our invention, these and other difficulties encountered with prior art sump pump switches are substantially reduced or eliminated.